well technically you're not really that wrong. since i'm quite close to the end-gear game. i'll give an overview of how the game normally progresses. hopefully this information helps out people.

dungeon level 50 - Density here will be quite low compared to other dungeons. Entering a dungeon by searching party (for bonus exp) got me to level 58 in just one single run. (this includes my level 11 family buff (10% exp additional) + 30% token bonus + searching party exp). this dungeon is great to grind with till you're level 70. after that it's not worth seeing that the mobs are only level 50 and you get heavy penalty going in. If you're between 75-90, i suggest rushing the dungeons to get talts/silver,gold bar/ etc for extra rewards.
dungeon level 90 - Density here is slightly more compared to others. People grind here between 90-114 before heading into the 115 dungeon. great items here are arde dagger which if you can help, will help you in your adventure very much. normally searching a party here can get you a party in 2 minutes.

dungeon level 115 - To be honest, not much people grind at this dungeon. most people would stick back to level 90 and rush it from there as they'll be hunting for arde dagger. at this point, most people goes to the mercenary post as one mission gives you close to 1 level from level 100 onwards.

dungeon level 130 - density here is alot of compared to other dungeons. reason being pentamion is gained here which can be sold somewhere around 4-5m for the recipe alone. most people would search to reap the exp benefits and chance to get that pentamion.

dungeon level 145 - it's quite alot here as well, for most, this is the last dungeon to go for before heading to level 175/190 dungeon. personally i'll train at 145 till 155/160 where i'll head to grinding next in order to get high exp per hour.

dungeon level 160 -  nobody goes here at all. low exp, no good loots.

dungeon level 175 - nobody really does full runs here. the only notable item to get here is ignition recipe and aias. exp here is bad.

the hard part is leveling from 160-190. personally, i'd save all cards from upon reaching level 100 and doing the dailies from mercenary post 5 times a day to get as much cards as possible. i highly recommend eating cards from 165-190. (you can also do it till 186 since the exp reset is there)

dungeon level 190 - exp here is extremely good upon reaching 190, 1 dungeon can give you 1 level at this time. tons of great items here to farm as well, sissel recipe, max pentamion recipe, magas items, venom as well if i'm not mistaken or viper.

dungeon level 200 - exp is bad here, people do it for catacombs items. particularly catacombs mace. most people rush here.

dungeon level 217 - exp is bad here as well. people do it for animus. most people rush here.

dungeon level 240 - personally i have not tried it. any items from 240 onwards are not tradable. Virtov items are really not worth the time at this point in my opinion, you may get wrong set items which takes away your time. i heard the exp here is not too bad, but i can't confirm since i've yet to try it out.

normally from level 210 and above you'd have to start the grind fest already.

210 - 228 - alemeth forest
228 - 251 - Evac / Igni Coast
252 - 268 - Storage
268+ - Mavern

this is just my personal experience as a level 258 templar and 133 fletcher in telsiai.